Lignins and Epoxidized Lignin-Based Biopolymers

Lignins are some of the most common natural polymers on Earth. They are located in vascular plant cell walls that are formed by randomly crosslinked phenolic molecules ensuring that plants are mechanically protected. Those biopolymers also possess antioxidant and antibacterial effects, aiding plants fight against biological and chemical attacks. The industrial and medical vastly fields benefit from the use of lignins and lignin-based biopolymers to produce antibacterial agents, antioxidant additives, UV protection agents, hydrogel-forming molecules, nanoparticles, and reinforcing agents or fillers in composite materials. By altering the lignin structure through epoxidation, lignins can be customized for particular uses and provide greater sustainability than conventional petrochemical-based resins. Green and sustainable methods of producing polymers have brought lignins and their derivatives at the top of research themes list because of their positive effects on environmental impacts of greenhouse gas emissions. The mechanical, thermal, and chemical characteristics of lignin-based epoxy resins are used in flame retardants with a high capacity for charring, in adhesives with superior mechanical and thermal qualities, and in coatings with UV-blocking and anticorrosion qualities. Epoxidized lignin-based biopolymers also show great potential in medical fields.